The present invention relates to a female connector to be provided at an end of a medical tube which is used for guiding, or introducing, a fluid and includes various tubes for blood circuits, or blood-supply or infusion tubes, and various catheter tubes. More specifically, the invention relates to a female connector in which a risk of inadvertent disconnection after being connected to a male connector is reduced.
A female connector provided on a medical tube for guiding a fluid is capable of connecting to a male connector provided on another tube or on an instrument. The female connector is formed with a specified female luer taper on an inner surface thereof, and with a specified male screw on an outer surface thereof. On the other hand, the male connector has a concentric dual cylindrical shape and is formed with a specified male luer taper on an outer surface of an inner cylinder, and with a specified female screw on an inner surface of an outer cylinder. Liquid-tightness or air-tightness of a connected portion between the female connector and the male connector is ensured by screwing the male screw of the female connector to the female screw of the male connector and by fitting the female luer taper of the female connector to the male luer taper of the male connector.
In the related art, when the female connector is connected to the male connector, the female connector is inserted onto the male connector while being screwed. Consequently, a tube connected to the female connector is twisted and its usability is impaired, and sometimes the female connector is disconnected from the male connector with the force of the twisted tube returning to its straight form. There is also a problem that when a load is exerted on the wings, which are provided for facilitating a tightening operation, in the direction of loosening the screw, liquid-tightness or air-tightness at the connected portion between the female connector and the male connector is immediately impaired.
As a measure for solving the twisting problem of the tube, female connectors which are divided into two parts, a core member and a housing member which are rotatable with respect to each other are already disclosed (European Patent No.0775501 and Japanese Patent Laid-Open No.313896/1999). With these female connectors, the twisting problem of the tube when the female connector is connected to the male connector is solved, and the risk of disconnection between both connectors due to the force of the twisted tube tending to restore straightness can be reduced.
However, with the female connectors of the prior art, in order to fit a recess on a housing and a projection on a core member to prevent disconnecting of the tube in an axial direction, the hardness of the core member must be selected. In order to do so, it is necessary to carefully select a material in order to form a core member which coheres to the male luer taper.
In addition, in order to establish a female connector having such a structure that the tube is not disconnected in the axial direction, a processing step to moderately soften the core member by heating during manufacturing is necessary. However, setting of conditions so that the core member is softened and deformed and the original shape of the core member is restored after being inserted into a housing is extremely difficult.
In the structure described above, the problem that liquid-tightness or air-tightness is impaired when a load which acts to loosen the screwing is exerted on the wings provided on the housing is not solved, and it is insufficient as a measure for preventing the tube from being disconnected.